<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>test</title>
</head>

<body style="display:flex;background-color: brown;height: 100vh;">

    <div style="width: 200px;z-index: 1;background-color: black;color: chartreuse;">iiiiii</div>

    <div style="display: flex;flex: 1;flex-direction: column;">
        <div style="height: 60px;z-index: 1;background-color: blue;">mmmmmmmmmmmmmmm</div>
        <div style="display: flex;flex-direction: column;">
            <div style="height:500px ;background-color: goldenrod;margin: 9px;"></div>
            <div style="height:500px ;background-color: goldenrod;"></div>
            <div style="height:500px ;background-color: goldenrod;"></div>
            <div style="height:500px ;background-color: goldenrod;margin: 9px;"></div>
            <div style="height:500px ;background-color: goldenrod;"></div>
            <div style="height:500px ;background-color: goldenrod;"></div>
            <div style="height:500px ;background-color: goldenrod;margin: 9px;"></div>
            <div style="height:500px ;background-color: goldenrod;"></div>
            <div style="height:500px ;background-color: goldenrod;"></div>
        </div>
    </div>
</body>

</html>